It is known to use large freight containers to hold goods and to ship these from one country to another. On arrival at the port of destination it is desirable to decontaminate the containers in case undesirable life forms, for example microbes, insects or other pests, have ridden the container from one country to another. It is an object of a preferred form of the invention to go at some way towards providing an useful alternative to known forms of container decontamination.